Avian pediatrics (Proceedings)

The pediatric avian patient can present with a wide variety of clinical conditions, many of which are specific to this age group. The purpose of this presentation is to present an overview of pediatric avian medicine including physical examination, diagnostic techniques and the most common clinical problems noted in this age group.

Birds are classified by their maturity level at hatching. Psittacines, passerines and pigeons are altricial, which means they are born naked and helpless with their eyes closed. Chickens, ostriches and waterfowl are born precocial, with down, eyes open, and the ability to walk and feed themselves at hatching. Psittacine neonates are totally dependent on the parent for food and warmth after hatch. Neonate birds lack a functional immune system and because of this are more susceptible to disease. Due to their helpless condition at birth and their increased susceptibility to disease, the conditions in which they are kept and their diet are extremely important to their overall health and survival. A baby bird with a poor start in life may develop clinical problems later in life as a result.

Chicks are either parent raised by their avian parent or a foster avian parent, or hand raised by humans. Most of the larger psittacine species are hand raised now due to the assumption by some that they make better long- term pets. There are advantages and disadvantages with each method of rearing. The health and development of psittacine chicks are dependent on several factors. Genetics, incubation, hatching, nutrition, environmental, developmental and disease factors must all be considered. There are several methods used for raising chicks, which include parent-raised chicks, hand fed chicks and fostering. The advantages of parent-raised birds are that the babies develop faster initially, and have a chance to develop species-specific behaviors, which will possibly make them better breeders. This method of rearing is also ideal for birds intended for reintroduction.

Early problems may not be picked up on in a parent-raised baby due to difficulty in monitoring closely. (Cockatiels, budgies and lovebirds may tolerate daily handling of their babies but larger birds are often more protective). Other problems which may arise are environmental problems in the nest box such as too hot or cold, dirty or damp, or problems with parasites. Hand-raising baby birds allows for increased production of the parent birds and can save sick or abandoned babies from the nest and potentially reduces the transmission of some diseases from parent to chick. This method is labor intensive and there is increased susceptibility to disease when babies are mixed. Also, there is a risk of management disease such as aspiration. Foster parenting involves removing a chick or eggs from the natural parents and placing them with another nesting pair. This can increase productivity and save chicks or eggs that might otherwise have been lost. The fostering parents have to be monitored to acceptance of the new chicks or eggs.

Nursery Management

When evaluating an ill chick, it is essential to evaluate the environmental conditions. The nursery should be separate from the adult bird areas and there should be separate caretakers for the adults and the babies. If the veterinary staff is visiting both the adult and nursery areas then the nursery area should be entered first and should ideally not be re-entered after adult bird exposure. This will minimize the risk of transmission of disease from adult birds to the neonates. Larger psittacines should be housed separately from budgies, cockatiels, lovebirds and conures who carry a higher risk of some diseases. For the most effective disease control, chicks hatched in the nest should be raised separately from chicks incubator hatched. The temperature and humidity should be evaluated and controlled to optimal conditions for the chicks. There may be species variability in the optimal environmental settings.

The temperature and humidity of the nursery area should be evaluated as part of the chick's physical examination process. General temperature guidelines are listed according to age: Newly hatched: 92 to 94 F, Unfeathered: 90 to 92 F, Pin feathered: 85-90 F, Fully feathered: 75-80 F, Weaned: 70 to 75 F.

The breeding and health history of the parents and siblings should be noted. Ask about problems during incubation and hatching. The type of brooder and substrate should be noted. The substrate should absorb moisture, provide good footing, and not cause digestive problems or obstruction if ingested. Discuss feeding and cleaning practices. As part of the history it is important to ask about the quarantine and evaluation of the health of new additions. Most nurseries have constant new bird additions, which increase the risk of disease introduction.

The type of diet fed should be noted, the volume and frequency of feeding, the temperature of the feeding, and the consistency of the formula (percentage of solids). A diet of approximately 25 to 30% solids (70 to 75 % water) should be fed after 1 or 2 days of age. Newly hatched babies should be fed a more dilute formula. The temp of the formula should be between102 and 106 degrees Fahrenheit. Young birds are most likely to have medical problems in the first week of life, at fledging and at weaning.

Physical Examination of the Chick

The chick should be kept warm during the examination process. Chicks should be examined just prior to feeding when possible. Birds with food in their crop should be handled carefully to reduce the risk of regurgitation and aspiration.

Overall Appearance and Attitude

Evaluate the attitude and feeding response of the chick. The body weight is important and it is helpful if the owner maintains and brings a body weight chart for that bird. Chicks should be weighed daily (in grams) prior to the first morning feeding. Growth for babies is slow for the first 1 to 4 days, than accelerates until weaning. Usually prior to weaning a baby will be at a weight that exceeds its adult weight. During weaning this extra weight is lost. Weight loss of approximately 10 % is acceptable during weaning if the body weight of a chick was adequate prior to the weaning process. Nestling birds sleep a lot and often sleep in odd positions. Baby birds often sit back on their hock joints rather than standing on their feet. There is little musculature over the keel until after fledging. Body condition can be assessed by evaluating the muscle and subcutaneous fat over the elbows, toes and hips. A record of developing characteristics is also helpful in determining if there were problems early in the development process. Important dates to note are the date the eyes opened, and the first appearance of head, tail and wing feathers. If possible compare the chick's development to other chicks of the same species and age.

Skin and Feathers

Normal chicks have yellowish-pink skin. Dehydrated chicks will have dry, hyperemic skin that feels sticky. If the skin of a neonate is pale and cold, it may need immediate attention. The head, wing and tails feathers will appear first. Abnormal feather growth can indicate the presence of stunting. Stress bars on the feathers indicate periods of stress (release of endogenous corticosteroids). Stress bars indicate a metabolic disturbance on the day that portion of a growing feather was forming. Feathers should be examined for normal emergence and should be examined for evidence of hemorrhage in the feather shafts or deformities.

Head, Heart,and Lungs

Evaluate the ear openings, make sure they have opened and if moisture is present, collect a culture. The ears open at hatching in old world psittacines. Macaws and eclectus have their ear canals covered with a membrane which in macaws will open day 23, in eclectus there will be a tiny opening within a couple of days. Eyes open in macaws between 14 and 21 days of age, in cockatoos between 10 and 21 days, and in amazons between 14 and 21 days of age. Abnormal placement of eyes under lids can indicate stunting. It is normal for the eyes to have a small amount of clear discharge right after opening. Evaluate the oral cavity for plaques or inflammation. Examine the choana for blunted papilla and evidence of papillomas in some species such as macaws, amazons and hawk-headed parrots. A normal feeding response characterized by a head bobbing motion should be elicited by stimulation at the lateral commissures of the beak. Heart rate varies from 180 to 400 beats per minute. Respiratory rate ranges from 20 to 40 breaths per minute.

Crop

The crop is larger in nestling birds and is usually two to three times the normal adult volume. Regular contractions of the crop should be visible and indicates normal motility. Palpation of the crop should be performed to determine crop wall thickness and assess contents. Crop wall thickening can be indicative of crop infection (fungal or bacterial).

The crop should be allowed to totally empty at least once a day. This is usually done over night. Crop stasis characterized by the inability of the crop to empty at a normal rate can indicate either a primary or secondary crop disorder. If indicated, swab samples of the crop mucosal lining can be obtained for cytology and culture.

Abdomen and Skeleton

Nestlings normally have a distended abdomen due to an enlarged proventriculus and ventriculus. Sometimes internal organs such as the liver, loops of intestines, and yolk sac can be viewed through the thin abdominal skin. Droppings are usually polyuric due to their liquid diet. Examine the spine and neck for abnormal curvature or weakness. Wings and legs should be examined for skeletal defects, swelling, wounds asymmetry and deviations. Evaluate the chick for normal posture, which is the ability to hold head up and move wings and legs.

Hematology and Chemistry

Nestling chicks have some common differences in their bloodwork results from adult birds: lower packed cell volumes, (20-30%), this is up to adult range by 9 to 11 weeks in most species, lower total protein (1-3 mg/dL), higher white blood cell count WBC (20,000-40,000 cells/uL) is common in young chicks. A transition from a heterophilia to lymphocytosis has been documented in some species of juvenile psittacines as they mature. The young bird's total WBC counts is usually down to the adult range at approximately nine to eleven weeks of age. Other findings include lower plasma albumin, lower uric acid, higher alkaline phosphatase (AP) and creatine kinase (CK). The jugular vein is the optimal location for venipucture in chicks due to their small size. Clipping a toenail is adequate for PCV and total solids (TS) but has proven to be unreliable for evaluating WBC.

Radiography

Nestlings have an enlarged proventriculus and ventriculus. The intestinal loops may also be dilated. The air sac space may be reduced due to the normal, larger gastrointestinal tract. The growth plates of the long bones will be open and the general muscle mass will be reduced.

Microbiology

Normal bacteria flora for chicks includes Lactobacillus, Bacilllus, Corynebacterium, non-hemolytic Streptococcus, Micrococcus and Staph. epidermidis. Theoretically a baby bird is born sterile. The chick develops bacterial flora as it is exposed to the environment.

Common Medical Conditions of Chicks

• Aspergillus fumigatus

• Aspiration pneumonia

• Bacterial disease

• Chlamydopila psittaci

• Bordetella avium

• Food-borne infections

• Beak trauma

• Congenital atresia of the choana

• Constricted toes

• Crooked toes

• Crop stasis

• Crop burn and fistula

• Delayed ear opening

• Esophageal and pharyngeal trauma

• Foreign body ingestion or impaction

• Gout

• Hepatomas

• Mandibular prognathism

• Metabolic bone disease

• Neck deformity

• Parasitic disease

• Regurgitation

• Rotational leg deformity

• Scissor beak

• Splay leg (spraddle leg)

• Stress bars

• Stunted growth

• Toe malposition

• Viral disease

• Yeast infections

Treatment of Pediatric Patients

Fluid Therapy

Chicks can become dehydrated easily. With 5% dehydration the skin will appear red and wrinkled. With 10% dehydration the chick may have cool extremities, reduced vein diameter, depression or lethargy. Shock or a coma condition can develop in the chick with 15% dehydration.

Lactated Ringers Solution (LRS) is the fluid of choice for most chicks and should be warmed to 38C prior to administration. Most sick birds are acidotic. The fluid deficit is replaced over 48 to 72 hours. Fluid maintenance therapy is 50ml/kg/day. Babies consume 2 to3 times the maintenance fluids that adult do. In a critical patient, fluids should be given intravenous (IV) or intraosseus (IO). The intraosseus catheter can be placed in the proximal femur, distal ulna or proximal tibiotarsal bone.

Blood transfusions should be considered if the packed cell volume (PCV) is below 15 %. You can give up to 5% of the bird's weight. Homologous blood transfusions have been shown to be of greater benefit.

Pharmacology

The total body water as a percentage of the total body weight in a hatchling is estimated to be 30 to 40 % higher than adults. Extracellular water, interstitial water, blood volume, and plasma volume are all higher in the neonate, which may affect drug distribution. Drug metabolism is slower in infants than adults. Renal excretion of antibiotics such as aminoglycosides is not as efficient in neonates, which may lead to a longer half-life. The blood brain barrier is more permeable in neonates. Some drugs used in adult birds may be detrimental to eggs or chicks. As with any drug usage, an avian pharmacological reference should be consulted for age-specific information and dosage prior to administration.

In chicks, antifungals are generally used along with antibiotics. Nystatin, fluconazole, and itraconazole are most commonly given. Nystatin requires a large volume and frequent administration and is not absorbed from the gastrointestinal tract. With debilitated chicks, begin antibiotics while culture results are pending. With gastrointestinal stasis, parenteral is recommended. Piperacillin is a broad-spectrum injectable that can be used in chicks. Oral antimicrobials often used in chicks include trimethoprim-sulfate and enrofloxacin. Oral trimethoprim sulfate has been reported to cause vomiting, facial flushing and depression in some macaws and lovebirds. Anti-inflammatories used in chicks include meloxicam, and aspirin. Dimethylsulfoxide (DMSO) can be used topically. Ivermectin, fenbendazole, and metronidazole are the most common antiparasite agents used in chicks. Fenbendazole has been known to cause feather problems in young growing birds. Metoclopromide can be used in young birds to stimulate the motility of the upper GI tract. Cisapride has been used in adult psittacines with no obvious side effects.

References

Clipsham R. Psittacine Pediatrics: Medicine, Surgery, and Management from Conception to Independence. In: Rosskoff Wand Woepel R's Diseases of caged and Aviary Birds 3rd edition 996;283-358.

Tully T. Evaluation of two lactobacillus acidophilus formulations as dietary supplements in neonatal cockatiels JAMS. Vol 12. #1. Mar 1998

Flammer K, Clubb S. Neonatology, In: Harrison and Harrison's Avian and Medicine: Principals and Applications. 1994;805-838

Clubb S. Psittacine Pediatric Husbandry and Medicine. In: Altman's Avian Medicine and Surgery. 1997;73-95.

Pediatrics: Part 1. Seminars in Avian and Exotic Medicine and Surgery, Vol 1, No 1 July 1992

Pediatrics: part 2. Seminars in Avian and Exotic Medicine and Surgery vol 2, No 3, July 1993

Clubb S, Wolf S, Phillips A. Psittacine Pediatric Medicine. In: Schubot R, Clubb K, Clubb S. Psittacine Aviculture: Perspectives, Techniques and Research 1992;16-1 to 16-26.